Wing-type sail system

ABSTRACT

A wing-type sail system is provided. The system includes a mast assembly pivotally mounted on a swiveling base attachable to a craft and a substantially rigid multi-element asymmetric wing pivotally attached to a top of the mast assembly. The system further includes a control mechanism for modifying roll and yaw of the substantially rigid wing with respect to the craft.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a wing-type sail system and, moreparticularly, to a rigid wing mid-mounted on a mast assembly configuredfor controlling the roll and yaw and optionally pitch and height of thewing with respect to a vessel.

Wing-type sails are known for use on both land and sea-type wind-poweredvehicles. By comparison with traditional soft sails, wing-type sails aretypically rigid or semi-rigid symmetrical airfoils that develop liftfrom the passage of wind thereupon; a wing-type sail is typicallymounted vertically and is pivotable about its vertical axis.

Generating useful propulsive force in any given direction requires theability to controllably align the angle of attack of the wing relativeto the direction of the wind.

Since mast-mounted wing-type sails need to convert a ‘lift’ force to aforward moving force under starboard and port wind directions, theprofile of the wing has to be symmetric (around the profilecenterline)—a less than optimal profile for maximizing lift forces.

Thus, it would be highly advantageous to have a wing-type sail systemdevoid of the above limitations.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided awing-type sail system comprising: (a) a mast assembly pivotally mountedon a swiveling base attachable to a craft; (b) a substantially rigidwing pivotally attached to a top of the mast assembly, the wing havingan asymmetric profile (airfoil); and (c) a control mechanism formodifying a roll and yaw of the substantially rigid wing with respect tothe craft.

According to further features in preferred embodiments of the inventiondescribed below, the wing is pivotally attached to a top of the mastassembly at a central portion thereof.

According to still further features in the described preferredembodiments the mast assembly forms a triangular tower.

According to still further features in the described preferredembodiments the wing is oriented to wind side by rolling the wing androtating the swiveling base.

According to still further features in the described preferredembodiments a top of the triangular tower is attached to the wingthrough a pin-type hinge.

According to still further features in the described preferredembodiments the mast assembly includes a plurality of mast poles eachbeing separately connected to the swiveling base and the wing.

According to still further features in the described preferredembodiments the control mechanism includes control wires for modifyingthe roll and yaw of the wing.

According to still further features in the described preferredembodiments the control mechanism is further capable of modifying aheight or pitch of the wing.

According to still further features in the described preferredembodiments a length of each of the plurality of mast poles istelescopically adjustable.

According to still further features in the described preferredembodiments the wing is pivotally attached to the mast assembly around acenter of gravity of the wing.

According to still further features in the described preferredembodiments the system further comprising wind speed and directionsensors mounted on the mast assembly and/or on the wing.

According to still further features in the described preferredembodiments the system further comprising a level angle sensor mountedon the swiveling base.

According to still further features in the described preferredembodiments the system further comprising a control unit for actuatingthe control mechanism according to information selected from the groupconsisting of wind speed, wind direction, vessel longitudinal direction,a level angle of the swiveling base, and an angle of the roll and yaw ofthe substantially rigid wing.

According to still further features in the described preferredembodiments the wing is foldable.

According to still further features in the described preferredembodiments the wing is telescopically foldable.

According to still further features in the described preferredembodiments the control unit is wired to the control mechanism.

According to still further features in the described preferredembodiments the control unit wirelessly communicates with the controlmechanism.

According to still further features in the described preferredembodiments the wing includes a leading edge and/or a trailing edgeextension.

According to still further features in the described preferredembodiments the extension is shaped as a winglet having an asymmetricairfoil shape.

According to still further features in the described preferredembodiments the winglet has an asymmetric profile.

According to another aspect of the present invention there is provided avessel comprising a plurality of the systems described herein.

According to still further features in the described preferredembodiments the vessel is a cargo ship, a tanker, a cruise liner or ayacht.

According to still further features in the described preferredembodiments the vessel further comprises a control unit for controllingeach control mechanism of the plurality of systems.

The present invention successfully addresses the shortcomings of thepresently known configurations by providing a wing-type sail systemwhich enables a user to control the roll and yaw of a substantiallyrigid asymmetric profile wing having a very high lift coefficient(C_(Lmax) higher than 3.0, up to about 4.5 or more) with respect to thevessel, thus enabling a user to optimize the angle of the wing withrespect to the wind.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. In case of conflict, the patentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice.

In the drawings:

FIG. 1 illustrates various airfoil shapes (wing profiles).

FIGS. 2a-e illustrate starboard to port tacking of a prior art symmetricwing-type sail.

FIG. 3 illustrates one embodiment of the present wing-type sail system.

FIGS. 4a-e illustrate starboard to port tacking of the wing-type sail ofFIG. 3.

FIG. 5 illustrates another embodiment of the wing-type sail system ofthe present invention.

FIG. 6 illustrates the swiveling base and mast assembly of the wing-typesail system of FIG. 5.

FIGS. 7a-b illustrate a vessel fitted with a plurality of the wing-typesail systems of FIGS. 3 and 5.

FIG. 8 is a flow chart diagram illustrating a closed control loopcontrol utilizable by the present system; Abbreviations: Vaz—Vesselazimuth; Waz—Apparent wind azimuth; Bangle—swiveling base angle relativeto vessel longitudinal centerline. Bangle=0 when Swiveling basecenterline align with vessel centerline. Bangle<0 when swiveling basecenterline points to starboard and Bangle>0 when swiveling basecenterline points to port side; 160>Bangle>−160; Wangle—wing angle invertical plane relative to base level; wangle=0 when wing is horizontal;wangle<0 when wing is angled left side (when looking from trailing edgeto leading edge) and Wangle>0 when wing is angled right side;90>Wangle>−90.

FIG. 9 is an image of a model boat fitted with a prototype systemconstructed in accordance with the teachings of the present invention.

FIGS. 10a-e illustrate a prototype multi-hull vessel (FIGS. 10a -b, d)fitted with a wing-type sail (FIGS. 10c-d ) constructed in accordancewith the teachings of the present invention. FIG. 10e illustrates theairfoil of the prototype wing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of a wing-type sail system which can be used asa propulsion or a propulsion-assist device on land or water vehicles.

The principles and operation of the present invention may be betterunderstood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

Rigid wing-type sails similar in structure and function to an aircraftwing are known in the prior art. Such sails provide sail-likefunctionality via a rigid, lift optimized structure which produces aforward ‘lift’ when mounted upright on a vessel, i.e. it produces aforce in the forward direction on the vessel thereby propelling thevessel forward.

Although rigid wing-type sails are efficient at harnessing the wind,they suffer from several inherent limitations.

Since wing-type sails are typically mounted upright on a vertical mastthe profile of such wings must be symmetric around the profilecenterline (FIG. 1 at B, centerline shown by dashed line) in order toenable generation of forward ‘lift’ under all tacking directions(starboard and port sail orientations). FIGS. 2a-e illustrates tackingunder changing wind/movement directions in a vessel with a symmetricwing-type sail mounted on an upright mast (W—wind direction, D—vesselsailing direction).

Although symmetric wing sails (FIG. 1 at B) can generate at least asmuch lift as an ordinary sail (FIG. 1 at A) they generate less lift thanan asymmetric airfoil wing sail (FIG. 1 at D and E). In order to solvethis limitation of symmetric wing sails, sail manufacturers have added atrailing edge winglet (See FIG. 1 at C) which increases the maximum liftcoefficient of the symmetric wing. Such a configuration is substantiallymore efficient in harnessing the wind than an ordinary sail and has beenutilized by boats racing the America's Cup.

Configurations utilizing mid-mounted pivoting wing-type sails are alsoknown. One example of such a sail system is the Aeroskimmer(www.dcss.org/speedweek/aeroskimmer.html). Although the Aeroskimmersolves most of the aforementioned problems, control over the wing and inparticular, adjusting wing alignment to changing wind directions isdifficult to achieve due to its mast system and its connection to thewing.

An asymmetric wing (asymmetric around the profile center line) generatesmore lift than a symmetric wing since it maximizes the difference in thespeed of air flowing over the top side (convex/cambered) and the bottomside (flat or concave). This in turn maximizes the static pressuredifference between the top and bottom surfaces of the wing and the liftforce pointing from the concave side to the cambered side (perBernoulli's law).

While reducing the present invention to practice, the present inventorhas devised a wing-type sail system that traverses the aforementionedlimitations of prior art systems to provide:

(i) an asymmetric wing sail having a maximum lift coefficient muchhigher than that of presently used wing sails for maximizing propulsionof small as well as large boats and ships;

(ii) a mast assembly that enables control over wing roll and yaw inorder to enable correct positioning of the wing sail profile withrespect to the wind to generate forward ‘lift’;

(iii) a mast assembly that is robust enough to support and move the wingsail to achieve optimized orientation with respect to the wind; and

(iv) an optional folding mechanism that enables folding and stowage ofboth wing and mast assembly.

Thus, according to one aspect of the present invention there is provideda wing-type sail system. As used herein, a wing-type sail refers to asubstantially rigid sail that has wing functionality. i.e. it cangenerate lift from air flowing over its surface. As used herein, thephrase “substantially rigid” refers to a wing structure that has a rigidcover. i.e. a cover that maintains its shape and is not dependent onwind for shaping.

The wing-type sail of the present invention can include a wing-likeframe (spars and profiles) covered with a stretched fabric, a polymer ora composite (fiberglass, carbon fiber). Alternatively, the wing-typesail of the present invention can be a solid structure composed of alightweight foam core that is covered with a composite.

The present system includes a mast assembly pivotally mounted on aswiveling base attachable to a water craft/vessel (e.g. yacht, racingboat, ship and the like) or a land craft/vehicle (e.g. land yacht). Theswiveling base can be attached to the deck or to a structure mounted onthe deck or hull. The present system further includes a substantiallyrigid wing pivotally attached to a top of the mast assembly, preferablyat the mid wing point (e.g. center of gravity) such that it balances ontop of the mast assembly.

The wing sail of the present invention has an asymmetric airfoil(profile) in order to maximize lift. An asymmetric profile isexemplified by D and E in FIG. 1.

Table 1 below lists the maximum lift coefficients of various wingprofiles. An asymmetric airfoil has a maximum lift coefficient that canbe 30-40% higher than that of an ordinary sail (FIG. 1 at A) and asymmetric profile wing (FIG. 1 at B). An asymmetric airfoil with aleading slat and trailing winglet can generate a maximum liftcoefficient of 4.5, three times the lift per m² of surface of anordinary sail.

TABLE 1 FIG. 1 Wing shape CLmax A Flat Cambered profile (sail) 1.5-1.3 BSymmetric profile 1.5 C Symmetric profile with trailing edge winglet2.5-2.8 D-E Asymmetric profile 1.5-2.0 F Asymmetric profile withtrailing edge winglet 3.1 G Asymmetric profile with leading slat and a4.5 trailing edge winglet

The wing sail of the present invention can also include leading and/ortrailing edge elements shaped as asymmetric (or symmetric) slats orwinglets (FIG. 1 at F and G) in order to further increase lift. As isshown in table 1 above, addition of such elements can increase themaximum lift coefficient by a factor of 2-3.

Various configurations of the wing sail of the present invention aredescribed in greater detail hereinbelow.

In order to enable an asymmetric wing to generate lift from winds of alltacking directions. i.e., to allow tacking in all directions while stillmaintaining forward lift, the wing sail of the present invention ismounted on a mast assembly that both rotates and flips the wing sailwhen tacked (i.e. controls both roll and yaw of the wing).

The mast assembly can include one or more masts (e.g. 1, 2, 4, 8 masts)that are attached to a swiveling base (turret) which is attached to thevessel. The top of the masts are attached to a mid portion (around or atthe center of gravity) of the wing sail via a hinge assembly which caninclude an axle/shaft/rod/pin fitted within friction/roller bearings.The hinge assembly enables the wing sail to roll around the hinge axisfrom an upright position (vertical or nearly vertical) on one side ofthe mast assembly to an upright position on an opposite side of the mastassembly (see description related to FIGS. 4a-e below for furtherdetail). The swiveling base can rotate the wing assembly such that theleading edge of the wing sail is correctly angled with respect to thewind to provide lift.

The mast assembly can alternatively include telescoping masts that canbe selectively actuated to roll the wing sail by lifting one side andlowering the other.

Various configurations of the mast assembly of the present invention aredescribed hereinbelow in greater detail.

The present system also includes a control mechanism for modifying aheight, pitch, roll and yaw of the wing with respect to the craft aswell as a wing span thereof.

The control mechanism can include winch motors, hydraulic pumps,mechanical or electric transmission, or the like for angling the mastassembly and for raising or lowering each of the masts. The controlmechanism preferably includes winch motors and pulleys which areattached via rigging (e.g. steel. Kevlar wires) to the top of the mastassembly and to the wing tips.

The control mechanism can be integrated or attached to the swivelingbase or it can be positioned below deck with wires running through thedeck to the mast assembly.

The present system further includes a control unit for enabling anoperator (e.g. ship captain) to control actuation of the mast assemblyand angle of the wing attached thereto via the control mechanism.

Referring now to the drawings, FIGS. 3-4 e illustrate one configurationof the wing-type sail system of the present invention which is referredto herein as system 10.

System 10 includes a mast assembly 12 which in this embodiment includes2 masts 14 attached via hinges or ball joints 16 to a base 18. Base 18can be circular (as shown in FIG. 3) or any other suitable shape(square, rectangular, star, cross, and the like). Base 18 can befabricated from galvanized plate steel or any other alloy (aluminumalloy), while masts 14 can be fabricated from aluminum, carbon fiber ora combination thereof. Base 18 can be mounted to a vessel 19 on acircular track/rail with rollers and a motor for rotating base 18 withinthe track.

Masts 14 can be telescopic to extend or retract to adjust a height andpitch of an attached wing 20. Masts 14 can include a spring mechanism(coil spring or an air piston) which is compressible when masts 14 arepulled down and retracted. When a pulling force is partially or fullyreleased, the compressed spring mechanism extends masts 14.

An asymmetric rigid wing 20 is attached on top of mast assembly 12through a hinge 22. Hinge 22 includes a pin running through centersection 21 of wing 20 between masts 14. The pin can rotate within centersection 21 or it can be fixed thereto and rotate against bearings inmasts 14. Hinge 22 allows wing 20 to roll from one side (FIG. 4a ) ofmast assembly 12 to the opposite side (FIG. 4e ). A control mechanism 32which includes motors and cables/chains/belts can be positioned withincenter section 21 and/or within masts 14 to control roll of wing 20.Alternatively, an external rigging of cables attached to wing 20 (attips or inward) and to pulleys and motors (similar to that described forsystem 100) can also provide the roll function.

Control mechanism 32 also controls rotation (swivel) of base 18 withrespect to the vessel by controlling one or more motors within base 18.

The skeleton (spars and profiles) of wing 20 is fabricated from analloy, a polymer, carbon fiber or wood and is covered with rigid orsemi-rigid panels (alloy, polymer, carbon fiber or cloth). Wing 20 canbe constructed from several foldable or telescopic segments (which canbe retracted/expanded via control mechanism) similar to wing 120 shownin FIG. 5.

Wing 20 can be fabricated with a variety of dimensions depending on thecraft and purpose. Typical dimensions for wing 20 can be selected from arange of 5 m in length, 1 m in width for small catamarans, trimarans orsailing boats, up to 50 m in length and 20 m in width for large super ormega yachts (single hull, catamarans or trimarans), or small, medium,large ships. Wing 20 can be a single foil (as shown in the Figures) or amulti-foil configuration (2, 3 or 4 sections) with the main wingattached to leading edge and/or trailing edge winglets (e.g. slats,flaperons or ailerons). As is described hereinabove, multi-foilconfigurations generate a high lift coefficient (C_(Lmax)>3) and arepreferred in all sea wind velocities. Wing 20 having a multi-foilconfiguration and C_(Lmax)=4.5 can provide about 280 Newton force per m²surface area at a typical wind speed of 10 m/s and 100 air temperature.

FIGS. 4a-e illustrate repositioning (tacking) of system 10 in order tochange sailing direction (D) under a steady wind (wind direction—D).FIGS. 4a-e illustrate a change of 70° in route direction in 14°increments. The vessel is turned 70° clockwise causing the winddirection to rotate 70° anti clockwise from front right to front left.In order to adjust the position of wing 20 according to the winddirection, wing 20 is rolled clockwise from −80° to +80° while base 18is rotated 34° counterclockwise [from +35°-18° (angle of attack) to−35°+18° (angle of attack)] relative to the vessel's longitudinalcenterline.

Such roll and yaw of wing 20 as affected through hinge 22 and mastassembly 12 can be used to reposition wing 20 to maximize lift under anychange in wind direction or vessel route.

The wing repositioning approach used by the present invention, whichseparates the roll and yaw function to two different mechanisms, allowsfor a stable and robust attachment between wing 20 and mast assembly 12,thus making the present invention suitable for use under any windcondition and with any size vessel and wing.

FIGS. 5-7 b illustrates another configuration of the wing-type sailsystem of the present invention which is referred to herein as system100.

System 100 includes a mast assembly 102 which in this embodimentincludes 4 masts 104 attached via hinges or ball joints 106 to a base108. Base 108 can be circular (as shown in FIGS. 5-6) or any othersuitable shape (square, rectangular, star, cross, and the like). Base108 can be fabricated from galvanized plate steel or any other alloy(aluminum alloy), while masts 104 can be fabricated from aluminum,carbon fiber or a combination thereof.

Masts 104 are preferably telescopic and include 2 or more segments(three shown) that can telescopically extend or retract to adjust aheight, pitch yaw or roll of an attached wing 120. Masts 104 can includea spring mechanism (coil spring or an air piston) which is compressiblewhen masts 104 are pulled down and retracted. When a pulling force ispartially or fully released, the compressed spring mechanism extendsmasts 104.

A substantially rigid asymmetric wing 120 is attached on top of mastassembly 102 through hinged/ball joints 22; wing 120 is preferablyseparately connected to each mast 104 through a dedicated hinge/balljoint 122.

The skeleton (spars and profiles) of wing 120 can be fabricated asdescribed above for wing 20. Wing 120 can be constructed from severalfoldable or telescopic segments 124 (which can be retracted/expanded viacontrol mechanism). In the embodiment shown in FIG. 5, wing 120 includes7 interconnected segments 124; with segments 126 and 128 beingtelescopically retractable into segment 130 (using mechanical orhydraulic mechanisms).

Wing 120 can be fabricated with a variety of dimensions depending on thecraft and purpose and can be a single foil (as is shown in the Figures)or a multi-foil configuration.

System 100 also includes a control mechanism 132 which includes motors134 with attached pulleys 136 (shown in detail in FIG. 6). Braided steelor aramid cables (guy wires) 138 (four shown) are spooled over pulleys136. Thus, motors 134 and attached pulleys 136 function as winches forpulling or releasing cables 138. Each pulley 136 functions independentlyto spool a cable 138 attached thereto. As is shown in FIGS. 5-6, a pair140 of cables 138 is preferably connected to each pulley 136 (cables 138can be a single cable looped over pulley 136). Each cable 136 of thepair is connected to a different portion of wing 120. For example, onecable 136 is connected to end of wing 120, while the other is connectedto a midsection of wing 120 at or near joint 122. Such a cablingconfiguration is important for ensuring that lift forces on wing 120 donot deflect it from its set position and that lift forces transferred tothe swiveling base and to the vessel by the wires are distributed.

Cables 138 enable control mechanism 132 to tilt wing 120 through pitch,roll and yaw while maintaining wing 120 stable at any angle with respectto any axis. By pulling on one or more cables 138, control mechanism cantilt wing 120 in any direction. Releasing (unspooling) cable 138 enablesmast 114 (retracted by pull of cable 138) to extend out via the springor hydraulic mechanism described above to any set height and wing 120angle.

In order to tack wing 120, control mechanism pulls cables 138 to swingwing 120 from an upright position on one side of mast assembly 102 tothe opposite side while mast assembly 102 swivels to correctly alignwing 120 to the desired angle of attack with respect to the wind. Thisroll and yaw movement is similar to that described above for system 10.

Systems 10 and 100 can also include any number of sensors for providingan operator with information relating to the position of wing 12 or 120,the vessel, as well as environmental information. Table 2 belowdescribes sensors that can be used with the present invention and theirlocation in systems 10 or 100.

TABLE 2 No. Sensor Units Location 1. Sailing azimuth Degrees Ship bridgeor vessel GPS 2. Apparent Wind Degrees at wing center direction onleading edge 3. Apparent Wind Meter/second at wing center speed onleading edge 4. Swiveling base Degrees On swiveling base level relativeto see level 5. Base center line angle Degrees On swiveling baserelative to (1) 6. Masts angle Degrees On bottom section relative to of1 mast Swiveling base level 7. Mast 1 length Meter On top of mast 1 8.Mast 2 length Meter On top of mast 2 9. Mast 3 length Meter On top ofmast 3 10. Mast 4 length Meter On top of mast 4 11. Wing roll DegreesBeneath wing C.G angle relative to see level 12. Angle of attack -Degrees Beneath wing Angle between C.G pointing base (5) and to leadingedge apparent wind direction (2)

Such sensors enable an operator to correctly position wing 12 or 120with respect to the wind and thus maximize a propulsive force obtainedfrom wing 12 or 120 with respect to a moving direction of the craft.

A typical sensor reading scenario is described in Table 3 below.

TABLE 3 No. Sensor Units Reading 1. Sailing azimuth Degrees 80 2.Apparent wind direction Degrees 340 3. Apparent Wind speed Meter/second11 4. Swiveling base level Degrees 0.5 relative to see level 5. Basecenter line angle Degrees −82 relative to (1) 6. Wing roll anglerelative Degrees 80 to see level 7. Angle of attack Degrees 18

Systems 10 and 100 further include a control unit (not shown),preferably positioned in the cockpit on the bridge. The control unitincludes a user interface for controlling control mechanism 32 or 132and for obtaining information related to a state of wing 20 or 120 (e.g.from above describe sensors), masts 14 or 114, swiveling base 18 or 118and any other component of system 10 or 100. The control unit is wiredto control mechanism 32 or 132 or is wirelessly connected thereto via anRF communication module.

The control unit can operate in an open loop mode, in which caserelevant information (from the sensors) is displayed to an operatorwhich then modifies wing 20 or 120 position accordingly, or it canoperate in a closed loop mode (auto-pilot) in which case, the computerof the control unit will make decision based on sensor data and courseplotted. In the closed loop mode, the operator can override computercontrol at any point in time. FIG. 8 illustrates closed loop controlover wing 20 or 120 and base 18 or 118 based on sensor data.

The control unit can include a touch screen display (e.g. a capacitivedisplay) for providing an operator with graphic or textual informationrelating to wing 20 or 120 (position, angles etc) and the angle of base18 or 118 with respect to the wind and sailing direction.

Any number of system 10 assemblies can be used on a craft. For example,a large water craft such as a tanker (FIGS. 7a-b ) can utilize severalsystem 10 or 100 assemblies (9 shown), each having a dedicated controlmechanism 32 or 132. Alternatively, one or more control mechanism 32 or132 can be used to control several mast/wing assemblies. In any case,control mechanism(s) 32 or 132 are preferably each controlled via asingle control unit which can also retrieve and display to an operatorsensor reading from each mast/wing assembly.

When utilized for propulsion in a water craft such as a 200,000 tontanker (FIGS. 7a-b ) a wing having 600 m² can provide, in case of CLmax4.5 and apparent wind velocity of 10 m/s (19.4 Knot) from a beam and airtemperature 100, a propulsive force of 169,000 Newton (N). Thus, tensuch system 10 or 100 assemblies (FIGS. 7a-b respectively) can provide apropulsive force of 1,690,000 N which can lead to considerable savingsin fuel.

Systems 10 or 100 of the present invention can be retrofitted onto anywater/land craft or it can be added to the craft during fabricationthereof (in a ship-building yard). Swiveling base 18 or 118 includes aring which that is mounted on bearings connected to the deck throughrods (welded or bolted to deck). The ring diameter equals the swivelingbase 18 or 118 diameter. Motors located on base 18 or 118 rotate agearwheel engaged to the ring or deck. On a small maritime vessel (e.g.yacht) one wing type sail system 10 or 100 will be mounted at around 30%of its length towards bow. On larger vessels 2-20 systems 10 or 100 canbe mounted along longitudinal center line, in one or more parallellongitudinal rows. For example system 10 or 100 with 500 m² wing 20 or120 area will be mounted for each 20K tons of a big ship in 2 parallellongitudinal rows with 100% (or more) of wing span clearance betweeneach system 10 or 100 (FIGS. 7a-b respectively).

When used in large see going freighters or tankers, the operation ofsystem 10 or 100 can be synchronized with the propulsion system of theship and with weather conditions while considering costs, voyagetimeline and on-time arrival at harbors.

Since on-time arrival at harbors is critical especially for cargo ships,efforts are made to maintain an average planned speed. Contribution ofwind propulsion generated by the present invention to the power neededto maintain that speed can vary between 0% and 100% depending upon windspeed and direction along the route. Wind conditions depend on dates,seasons and global location. In head winds between 30° and −30° there isno contribution of wind power. In apparent wind angle of 90° or −90°,wind speed in access of 12 m/s and vessel's planned speed of 14 Knotsthe wind propulsion could provide 80%-100% of the power needed. Theperfect angle of the wings relative to the wind is automatically andcontinuously controlled by a control unit of the present invention(receiving input from sensors—wind direction and speed, vessel's sailingdirection) and produce output to activate electro mechanical units thatmaneuver the wings. Any voyage is planned in advance according toweather conditions along the planned route at the planned dates, and theamount of fuel needed (or saved) is calculated automaticallycomputationally.

As used herein the term “about” refers to ±10%.

Additional objects, advantages, and novel features of the presentinvention will become apparent to one ordinarily skilled in the art uponexamination of the following examples, which are not intended to belimiting.

EXAMPLES

Reference is now made to the following examples, which together with theabove descriptions illustrate the invention in a non limiting fashion.

Example 1 Model Boat with a Wing Sail System

FIG. 9 is an image of a model boat fitted with a prototype system 100.The model is a 1 meter mono hull built from Styrofoam reinforced withaluminum bars. The model has a large hydrodynamic keel made of iron andis covered by a smooth sheet of stainless steel and includes a ruddermade of aluminum pole and stainless steel sheet. The prototype wing sailsystem includes 2 parallel masts built from welded aluminum poles. Themast assembly can rotate 180° clockwise or counterclockwise around thecenter mast which is inserted into the hull. The wing span is 1.45meters, and has an aspect ratio of 10; it is fabricated from condensedStyrofoam laminated with fiberglass. The wing is connected to the mastsby horizontal axis allowing it to rotate 180° clockwise or anticlockwise. Rudder, masts assembly rotation and wing angles (viaailerons) are all remote controlled.

The model was tested in a 400×100 meters pool, in an 18 knots northwestwind. During the test the model was sailed in various directions withgenerally satisfying results.

Example 2 Catamaran with a Wing Sail System

A 4 hull catamaran fitted with system 10 was designed (FIG. 10a ) andconstructed. A fifth hull (arrow in FIG. 10b ) was added to theprototype during construction in order to better support the weight ofthe mast assembly and wing. The hulls were fabricated from fiberglassand reinforced aluminum struts and assembled to form a catamaran that is4.4 meters wide and 7.2 meters long (FIG. 10d ). A 1.9 m swiveling basewas fabricated from stainless steel; the base swivels on 8 pairs ofbearings. The mast assembly was constructed from stainless steel strutsconnected via pins and hinges to 6 points on the swiveling base. Themast assembly is 1.86 meters in diameter and 4.20 meters in height.

The wing-type sail (FIG. 10c-d ) includes a main airfoil element and atrailing edge winglet (FIG. 10e ). The wing was fabricated from 40airfoil sections of aluminum and birch ‘sandwiches’. The overall lengthof the wing is 7.96 meter and the width is 1.32 meter. The prototypecatamaran was tested successfully in a 7 knot wind (FIG. 10d ).

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

1. A wing-type sail system comprising: (a) a mast assembly pivotallymounted on a swiveling base attachable to a craft; (b) a substantiallyrigid wing pivotally attached to a top of said mast assembly, said winghaving an asymmetric profile; and (c) a control mechanism for modifyinga roll and yaw of said substantially rigid wing with respect to thecraft.
 2. The system of claim 1, wherein said wing is pivotally attachedto a top of said mast assembly at a central portion thereof.
 3. Thesystem of claim 1, wherein said mast assembly forms a triangular tower.4. The system of claim 1, wherein said wing is oriented to wind side byrolling said wing and rotating said swiveling base.
 5. The system ofclaim 3, wherein a top of said triangular tower is attached to said wingthrough a pin-type hinge.
 6. The system of claim 1, wherein said mastassembly includes a plurality of mast poles each being separatelyconnected to said swiveling base and said wing.
 7. The system of claim1, wherein said control mechanism includes control wires for modifyingsaid roll and yaw of said wing.
 8. The system of claim 2, wherein saidcontrol mechanism is further capable of modifying a height or pitch ofsaid wing.
 9. The system of claim 6, wherein a length of each of saidplurality of mast poles is telescopically adjustable.
 10. The system ofclaim 1, wherein said wing is pivotally attached to said mast assemblyaround a center of gravity of said wing.
 11. The system of claim 1,further comprising wind speed and direction sensors mounted on said mastassembly and/or on said wing.
 12. The system of claim 1, furthercomprising a level angle sensor mounted on said swiveling base.
 13. Thesystem of claim 1, further comprising a control unit for actuating saidcontrol mechanism according to information selected from the groupconsisting of wind speed, wind direction, vessel longitudinal direction,a level angle of said swiveling base, and an angle of said roll and yawof said substantially rigid wing.
 14. The system of claim 1, whereinsaid wing is foldable.
 15. The system of claim 14, wherein said wing istelescopically foldable. 16-17. (canceled)
 18. The system of claim 1,wherein said wing includes a trailing edge extension and/or a leadingedge.
 19. The system of claim 18, wherein said trailing edge extensionis shaped as an winglet and said leading edge extension is shaped as aslat.
 20. The system of claim 19, wherein said winglet has an asymmetricprofile.
 21. A vessel comprising a plurality of the systems of claim 1.22. (canceled)
 23. The vessel of claim 21, further comprising a controlunit for controlling each control mechanism of said plurality ofsystems.